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15° to the axis of the tube by the two deflecting
plates.
3. Technical data
Filament voltage:
Anode voltage:
Anode current:
Deflector plate
voltage:
Distance between
plates:
Fluorescent screen:
Glass bulb:
Total length:
4. Operation
To perform experiments using the electron-beam
deflection tube, the following equipment is also
required:
1 Tube holder D
2 High voltage power supply 5 kV (115 V, 50/60 Hz)
or
2 High voltage power supply 5 kV (230 V, 50/60 Hz)
1 Helmholtz pair of coils D
1 DC power supply 20 V (115 V, 50/60 Hz)
or
1 DC power supply 20 V (230 V, 50/60 Hz)
1 Analogue multimeter AM51
Additionally recommended:
Protective Adapter, 2-Pole
4.1 Setting up the tube in the tube holder
The tube should not be mounted or removed
unless all power supplies are disconnected.
Push the jaw clamp sliders on the stanchion
of the tube holder right back so that the jaws
open.
Push the bosses of the tube into the jaws.
Push the jaw clamps forward on the stan-
chions to secure the tube within the jaws.
If necessary plug the protective adapter onto
the connector sockets for the tube.
≤
7,5 V AC/DC
1000 V – 5000 V DC
0.1 mA approx. at 4000 V
5000 V max.
54 mm approx.
90 mm x 60 mm
130 mm Ø approx.
260 mm approx.
1008507
1003309
1003310
1000644
1003311
1003312
1003074
1009961
4.2 Removing the tube from the tube holder
To remove the tube, push the jaw clamps
right back again and take the tube out of the
jaws.
5. Example experiments
5.1 Magnetic deflection
Set up the tube as in Fig. 2. Connect the mi-
nus-pole of the anode voltage to the 4-mm
socket marked with a minus.
Insert the Helmholtz tubes into the holes of
the tube holder.
Turn on the high-tension power supply.
Energise the Helmholtz coils and observe
the path of the beam.
The path of the luminous beam is circular, the de-
flection being in a plane perpendicular to the elec-
tromagnetic field.
At fixed anode voltage the radius decreases with
increasing coil current.
With a fixed coil current the radius increases with
increasing anode potential, indicating a higher
velocity.
An electron of mass m and charge e moving per-
pendicular to a uniform magnetic field B at veloc-
ity v is deflected by the Lorentz force Bev onto a
circular path of radius r.
m
v
B
e
v
r
5.2 Electric deflection
Set up the tube as in fig 3. Connect the mi-
nus-pole of the anode voltage to the 4-mm
socket marked with a minus.
Turn on the high-tension power supply.
Switch on the deflector plate voltage and ob-
serve the path of the beam.
An electron with velocity v passing through the
electric field E produced by a plate capacitor held
at a voltage U
with a plate spacing d is deflected
P
into the curved path of a parabola governed by
the equation:
1
e
y
2
m
where y is the linear deflection achieved over a
linear distance x..
2
2
(1)
E
2
x
(2)
2
v
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